Seasonal and interannual fluctuations of the Angola-Benguela Frontal Zone (ABFZ) using 4.5 km resolution satellite imagery from 1982 to 1999

Eighteen years of 4.5 km resolution satellite sea surface temperature (SST) data are used to analyse the surface expression of the Angola-Benguela Frontal Zone (ABFZ). The ABFZ is the convergence zone of the southward-flowing Angola Current and the northward extent of the Benguela Upwelling regime. The analyses presented have benefited from the extensive, high temporal and spatial (4.5 km) resolution of the data, made possible by satellite remote sensing. The ABFZ is identified as a region of closely spaced isotherms representing consistently sharp SST gradients. These SST gradients are indicative of the frontal zone, and its seasonal and interannual variability (including characteristics such as width, offshore extent, orientation and intensity). Aside from a long-term intensification of the front, interannual variability of the ABFZ is also shown to be affected by warm and cool anomalies that occur periodically in the south-east Atlantic Ocean. Such anomalies and the reaction of the frontal zone to them are discussed.